Fuel Cells/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim stands in a variety store. He holds a gaming device. The device beeps as he plays with it, and then indicates it is running out of power. TIM: Oh, no, no, no! Moby joins Tim. TIM: How can the batteries be dead already? I forgot to save. Tim reads from a typed letter. TIM: Dear Tim and Moby, I've been hearing a lot about fuel cells. What are they? From, Austin. Fuel cells are electrochemical devices that convert a fuel's chemical energy directly into electrical energy. Since no fuel is getting burned, fuel cells generate power more efficiently than a combustion engine. And fuel cells give off water instead of carbon dioxide, so they don't cause the pollution that combustion engines do. An animation shows oxygen and hydrogen floating into a fuel cell and water and power floating out of it. MOBY: Beep. TIM: Uh, okay. Let's back up a second, combustion engines like the one you find in a car burn fossil fuels for power. You can watch our "Car" movie to see exactly how this works. An animation shows a combustion engine's piston generating power. TIM: Burning fossil fuels produces chemicals like carbon dioxide, which contributes to pollution. Dark gray smoke comes out of the combustion engine and fills the screen. TIM: Also, a combustion engine is only about twenty percent efficient. An animation shows a gasoline can. TIM: That means you're only getting back twenty percent of the energy stored up in the fuel. The gasoline can becomes see-through to show only twenty percent of its energy as Tim describes. MOBY: Beep. TIM: Yeah, that's a waste. Fuel cells can reach efficiency levels closer to around 40%. The most common type of fuel cell is powered by hydrogen gas. It's a little like a battery, with a positively charged cathode and a negatively charged anode. Sandwiched between the anode and the cathode is the electrolyte, which is coated with a catalyst. An animation shows a fuel cell in a car. The car disappears. The fuel cell enlarges and divides into three layers. The top layer is labeled "anode," the bottom layer is labeled "cathode," and the middle layer is labeled "electrolyte (catalyst)." TIM: A molecule of oxygen gas, or "O2" on the cathode is split by the catalyst into two separate oxygen atoms, which both have a negative charge. When an "H2" molecule is supplied to the anode it hits the catalyst, which causes it to split into two hydrogen ions and two electrons. The positively charged hydrogen ions flow to the cathode, attracted by the negatively charged oxygen atoms. The electrons flow to the cathode along a separate path, where their flow can be used as electricity. An animation shows the process Tim describes. TIM: Then all the parts recombine to form 2H20,or water. The animation shows water molecules in front of the fuel cell. TIM: A fuel cell is charged up with hydrogen and oxygen, and since these gasses can be compressed, fuel cells can have a large storage capacity. MOBY: Beep beep. TIM: Well, fuel cells aren't too common yet, because the kinks of cheap mass production are still being worked out. But hey, once they get going, look out world! Fuel cells could be used to cleanly power cars, streetlights, cell phones, or even eh, video games. Images show a car, a streetlight, a cell phone, and a video game. Then Tim shakes his powerless gaming device, which rattles. Moby uses a finger device to power up the device. TIM: Wow. You're the best, Moby! Tim becomes immediately absorbed in his gaming device, which beeps quickly and loudly. Tim mumbles as he plays. TIM: Got to catch them all. Moby rolls his eyes. Category:BrainPOP Transcripts Category:BrainPOP Engineering & Technology Transcripts Category:BrainPOP Science Transcripts